-LRB- CNN -RRB- -- The fight boxing fans have long been clamoring for has moved a step closer , with undefeated Floyd Mayweather challenging Manny Pacquiao to a showdown on May 5 -- but will it happen ?

Hopes of the much-anticipated bout dimmed in December when Mayweather , the WBC welterweight champion , was sentenced to a 90-day prison term after being found guilty of domestic violence .

However , a Nevada judge ruled last week that the American , who has won all 42 of his professional fights -LRB- 26 by knockout -RRB- , could delay reporting to jail until June because he had already lined up a fight in May .

And now the 34-year-old has revealed he wants his opponent to be the Philippines ' WBO champion -- his longtime rival for the title of best pound-for-pound boxer , and a man he failed to agree a deal with in 2010 after insisting on Olympic-style pre-bout blood testing .

Mayweather chose micro-blogging website Twitter to issue his challenge .

`` Manny Pacquiao I 'm calling you out let 's fight May 5th and give the world what they want to see , '' he wrote on Tuesday .

`` My jail sentence was pushed back because the date was locked in . Step up punk . ''

However , Pacquiao -- who retained his WBO title in his third meeting with Juan Manuel Marquez in November -- issued a statement via his website saying he does not want to fight on that date .

`` Manny Pacquiao wants to make it clear the fight can happen at the end of May -- Manny wants Floyd to release his grip on May 5th , so the fight can happen for the fans , '' Wednesday 's statement read .

Pacquiao has an impressive record , with 54 wins from 59 bouts -- 38 by knockout -- plus three losses and two draws . He is the first man in the sport 's history to have won world titles in eight weight divisions .

The 33-year-old is rated by Ring Magazine as the best pound-for-pound fighter in the world , with Mayweather second on the 10-man list following September 's knockout win over compatriot Victor Ortiz in Las Vegas .

Pacquiao has also launched a successful political career and was elected into the Philippine House of Representatives in June 2010 .

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Floyd Mayweather has challenged Manny Pacquiao to a fight on May 5

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Mayweather was sentenced to three months in jail for domestic violence in December

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The American received permission to delay reporting to jail in order to fight in May

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But Pacquiao says he would prefer to finally face his rival at the end of the month